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Characteristics of wastewater discharges from coal-fired power plants

page 690

CHARACTERISTICS OF WASTEWATER DISCHARGES
FROM COAL-FIRED POWER PLANTS
Tien-Yung J. Chu, Environmental Engineer
Richard J. Ruane, Supervisor Special Projects Staff
Gerald R. Steiner, Environmental Engineer
Water and Wastewater Section
Tennessee Valley Authority
Division of Environmental Planning
Water Quality and Ecology Branch
Chattanooga, Tennessee 37401
INTRODUCTION
The nonthermal wastewater discharges from fossil-fueled power plants have only recently gained the attention of environmental regulatory authorities. Before the enactment of the Federal Water Pollution Control Act as amended in 1972 (PL 92-500), very
little was known about the characteristics of the various wastewater discharges from fossil-fueled plants. At that time the limited data that were available indicated considerable
differences between power plants, but provided little information to explain these
differences.
The Tennessee Valley Authority (TVA) initiated a random sampling program in 1967.
The first discharges to be monitored were surface water discharges from coal ash disposal
ponds. In 1970, TVA began collecting weekly grab samples and analyzed the samples
for pH, alkalinity, hardness, conductivity, total and dissolved solids, and turbidity. Quarterly grab samples collected since 1968 have been analyzed for eight additional parameters
(Ca, Mg, CI, Na, Fe, Mn, SO4 and Si) and those collected since 1973 have also been
analyzed for trace metals (Al, As, Ba, Be, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag and Zn), phosphorus, ammonia nitrogen and cyanide.
More recently, projects were initiated to characterize other wastewater discharges.
These discharges included boiler-tube chemical cleaning wastes, lime and limestone sulfur
dioxide scrubber wastes, coal pile drainage, ash pond leachates, and chlorinated cooling
water discharges. In addition, the factors that affect the characteristics of these discharges
are being delineated.
Work is being carried out to define the contaminants in these chemical effluents that
have the potential for causing environmental effects, so that evaluations of treatment
processes or other corrective measures can be initiated as needed. The Environmental
Protection Agency (EPA) promulgated effluent limitations guidelines in 1974 for the
achievement, by 1977, of best practicable control technology currently available (BPCTCA)
and, by 1983, of best available technology economically achievable (BATEA) for the
steam-electric power-generating point source category. The summary of EPA effluent
guidelines for chemical discharges from steam-electric power-generating plants is shown
in Table I.
Although plans are being prepared by utilities for compliance with the EPA guidelines,
more information about the characteristics of power plant chemical discharges is needed.
Limited data on these nonthermal wastes were presented by EPA in 1974 [1). A recent
review of the literature [2-8] indicated that only cooling tower blowdown and boiler
blowdown had received reasonably sufficient attention. These waste streams were found
to be a function of makeup water quality, fuel type, system type, thermal efficiency and
cycles of system operation.
This paper provides information on characteristics of ash pond effluents, chemical cleaning wastes, lime and limestone scrubber wastes, and coal pile drainage. This paper also
discusses some methods for treating these waste streams.
690

CHARACTERISTICS OF WASTEWATER DISCHARGES
FROM COAL-FIRED POWER PLANTS
Tien-Yung J. Chu, Environmental Engineer
Richard J. Ruane, Supervisor Special Projects Staff
Gerald R. Steiner, Environmental Engineer
Water and Wastewater Section
Tennessee Valley Authority
Division of Environmental Planning
Water Quality and Ecology Branch
Chattanooga, Tennessee 37401
INTRODUCTION
The nonthermal wastewater discharges from fossil-fueled power plants have only recently gained the attention of environmental regulatory authorities. Before the enactment of the Federal Water Pollution Control Act as amended in 1972 (PL 92-500), very
little was known about the characteristics of the various wastewater discharges from fossil-fueled plants. At that time the limited data that were available indicated considerable
differences between power plants, but provided little information to explain these
differences.
The Tennessee Valley Authority (TVA) initiated a random sampling program in 1967.
The first discharges to be monitored were surface water discharges from coal ash disposal
ponds. In 1970, TVA began collecting weekly grab samples and analyzed the samples
for pH, alkalinity, hardness, conductivity, total and dissolved solids, and turbidity. Quarterly grab samples collected since 1968 have been analyzed for eight additional parameters
(Ca, Mg, CI, Na, Fe, Mn, SO4 and Si) and those collected since 1973 have also been
analyzed for trace metals (Al, As, Ba, Be, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag and Zn), phosphorus, ammonia nitrogen and cyanide.
More recently, projects were initiated to characterize other wastewater discharges.
These discharges included boiler-tube chemical cleaning wastes, lime and limestone sulfur
dioxide scrubber wastes, coal pile drainage, ash pond leachates, and chlorinated cooling
water discharges. In addition, the factors that affect the characteristics of these discharges
are being delineated.
Work is being carried out to define the contaminants in these chemical effluents that
have the potential for causing environmental effects, so that evaluations of treatment
processes or other corrective measures can be initiated as needed. The Environmental
Protection Agency (EPA) promulgated effluent limitations guidelines in 1974 for the
achievement, by 1977, of best practicable control technology currently available (BPCTCA)
and, by 1983, of best available technology economically achievable (BATEA) for the
steam-electric power-generating point source category. The summary of EPA effluent
guidelines for chemical discharges from steam-electric power-generating plants is shown
in Table I.
Although plans are being prepared by utilities for compliance with the EPA guidelines,
more information about the characteristics of power plant chemical discharges is needed.
Limited data on these nonthermal wastes were presented by EPA in 1974 [1). A recent
review of the literature [2-8] indicated that only cooling tower blowdown and boiler
blowdown had received reasonably sufficient attention. These waste streams were found
to be a function of makeup water quality, fuel type, system type, thermal efficiency and
cycles of system operation.
This paper provides information on characteristics of ash pond effluents, chemical cleaning wastes, lime and limestone scrubber wastes, and coal pile drainage. This paper also
discusses some methods for treating these waste streams.
690